This invention relates generally to high speed antifriction bearings, and, more particularly, to a roller bearing of improved reliability.
In general, an antifriction bearing of the roller bearing type finds its greatest utility by being interposed between a stationary and a rotating member or two rotating members in order to substantially reduce the friction therebetween. Such a roller bearing generally comprises an inner ring and an outer ring, the inner ring being fixedly secured to a rotating shaft. Situated between the inner ring and outer ring are a plurality of cylindrical rollers. The rollers are generally held in spaced apart relationship by a cage, separator or retainer. As the shaft rotates, the inner ring rotates with respect to the outer ring, with the cage and rollers also rotating. As the speed of the shaft increases, the friction generated by the relative motion between the cage, rollers and rings increases.
Generally, roller bearing reliability has kept up with the state-of-the-art primarily through the tightening of manufacturing tolerances thereby resulting in substantially increased manufacturing costs. As higher speeds and more severe loading and alignment conditions arise the manufacturing limits of roller bearings are being reached.
Experience has shown us that roller instability (eccentric and wear) can occur in bearings at speeds as low as 1 million DN (DN=bearing bore in mm.times.shaft RPM). At speeds greater than 1 million DN continuous bearing operation requires uniform oil distribution through the bearing in order to reduce wear. The above problems have created unreliability in the use of roller bearings. Therefore, there exists a need to not only provide a roller bearing which is cost efficient but is also capable of overcoming roller instability problems as well as effectively providing uniform lubrication to the moving parts of the bearing.